a. Field of the Invention
The present invention generally relates to laser devices and methods and more specifically to laser devices and methods used in medical imaging, diagnostics and treatment, various industrial applications such as etching, military applications, and is also useful for treatment of nuclear waste and energy production.
b. Description of Related Art
Laser technology has experienced widespread acceptance and has been put to numerous uses in many aspects of everyday life. Lasers have found their way into the medical industry and their use is expanding rapidly. Lasers are also used in industrial applications such as etching, welding and the like. Similarly, with the intense energy output that lasers provide, there has also been interest in military applications and uses of lasers. Despite the state of laser technology there is a need for new and improved laser technology. Moreover, conventional laser technology, although useful, has proven inefficient, requiring much higher amounts of energy to achieve the laser effect which has often proven impracticable.
With the unlocking of atomic secrets and the advent of nuclear technology, humanity has received many benefits. However, through the use of nuclear technology problems have arisen that even advancing technology has been incapable of handling, namely how to deal with the radioactive waste created through the nuclear process. Currently, nuclear waste is essentially put into storage until the radioactive waste can be moved to a more proper location or the radioactivity lessens to background levels. Both pose a multitude of problems. In the first instance, to date there have been few promising ways of safely locking nuclear waste in a form that does not degrade and contaminate the environment. One technology for the safe storage of nuclear waste is a process called vitrification which essentially locks the waste into glassy medium which is then stored in containers. However, this process is extremely expensive and the long-term stability of such waste is unknown. Likewise, although governments have spent billions of dollars in a search for a suitable permanent nuclear waste repository the efforts so far have been fruitless. Other methods of treating nuclear waste have been proposed but none has proven to be sufficiently cost effective and safe to meet the ever-increasing demand to deal with nuclear waste.
Thus there is a need to effectively, safely and cost-effectively dispose of nuclear waste.
In accordance with one aspect of the present invention, a laser useful for medical imaging, diagnostics and treatment and associated methods are provided. In accordance with another aspect of the present invention, a laser useful for industrial applications such as etching and associated methods are provided. In accordance with another aspect of the present invention, a laser suitable for military applications is provided. In accordance with still another aspect of the present invention, a treatment system and method for nuclear waste through coordinated, spontaneous accelerated decay of radioactive nuclei is provided. In accordance with a related aspect of this invention, the release of the nuclear decay laser to produce another form of energy, such as electricity, is provided.
In accordance with the invention, a nuclear decay laser device is provided. The nuclear decay laser device in accordance with the invention includes at least a radioactive element, a magnetic field source associated with the radioactive element for generating and subjecting the radioactive element to a magnetic field external to the radioactive element. A source of radio frequency energy is provided for subjecting the radioactive element to a radio frequency energy tuned to the Larmor frequency of the precessing radioactive nuclei of sufficient intensity to flip the radioactive nuclei to a flip angle sufficient to allow the radioactive nuclei to release energy in the form of electromagnetic radiation and/or particles upon relaxation of the radioactive nuclei caused by termination of the radio frequency energy.
In accordance with another aspect of the invention, a nuclear decay laser imaging device, suitable for medical imaging and other imaging purposes is provided. The nuclear decay laser imaging device in accordance with the invention comprises at least one radioactive element, a magnetic field source associated with the radioactive element for generating and subjecting the radioactive element to a magnetic field external to the radioactive element. A source of radio frequency energy is provided for subjecting the radioactive element to a radio frequency energy tuned to the Larmor frequency of the precessing radioactive nuclei of sufficient intensity to flip the radioactive nuclei to a flip angle sufficient to allow the radioactive nuclei to release energy in the form of electromagnetic radiation and/or particles upon relaxation of the radioactive nuclei caused by termination of the radio frequency energy. A specimen area is provided for placing matter to be imaged by the released energy and detecting structure is provided for detecting the interaction of the released energy with the matter placed in the specimen area. Any suitable detection or imaging structure can be utilized, such as X-ray film, a CT scanner or a suitable electronic detecting device, for example.
In accordance with another aspect of the present invention, a method for the treatment of nuclear waste composed of a radioactive element is provided. The method includes the steps of placing the nuclear waste in the magnetic field external to the nuclear waste, subjecting the nuclear waste to a radio-frequency wave tuned to the Larmor frequency of the precessing radioactive nuclei of the radioactive element, providing the radio-frequency pulse with sufficient strength and duration to flip the radioactive nuclei such that the relaxation of the radioactive nuclei will release energy in the form of heat, electromagnetic radiation and/or particles. The flipped radioactive nuclei are allowed to relax thereby releasing their energy and accelerating the rate of decay of the radioactive nuclei relative to the normal rate of decay of said nuclei.
In accordance with another aspect of the present invention, a method for producing electrical energy from nuclear waste is provided. The method includes the steps of placing the nuclear waste in the magnetic field external to the nuclear waste and subjecting the nuclear waste to a radio-frequency wave tuned to the Larmor frequency of the precessing radioactive nuclei of the nuclear waste. The radio-frequency pulse is provided with sufficient strength and duration to flip the radioactive nuclei such that the relaxation of the radioactive nuclei will release energy in the form of heat, electromagnetic radiation and/or particles. The flipped radioactive nuclei are allowed to relax thereby releasing their energy. A structure is provided for absorbing the released energy to directly or indirectly produce electric current.
In one embodiment, at least one type of radioactive material which possesses an angular momentum and magnetic moment is encompassed within a cylindrical magnet, preferably of at least 1 Tesla, wherein the center of the magnet has been removed along the lengthwise axis of the magnet to accommodate placement of the radioactive material within the magnet. As is typical with conventional MRI devices, the cylindrical magnetic core is surrounded by an outer cryoshield and inner magnetic windings. Homogeneity of the magnetic field can be achieved through shim coils, for example. Gradient recall pulse sequences are generated by gradient coils. The radioactive specimen is surrounded by a cylindrical transmit-receive radio-frequency (RF) coil such that the open end of the RF coil is directed along the axis of the magnet defined by the direction of the main magnetic field Bo.
When the radioactive nuclei are placed in the external magnetic field Bo, the nuclei precess about the external magnetic field vector Bo. The frequency of this precession is defined by the Larmor equation. The RF coil is tuned to the Larmor frequency of the radioactive nuclei placed in the magnetic field to produce an RF pulse having a frequency that is matched to the Larmor frequency of the precessing nuclei. This is accomplished using the Larmor equation:
xcfx89=xcex3xc2x7Bo
where
xcfx89 is the frequency of nuclear precession about the main external magnetic field vector Bo;
xcex3 is the gyromagnetic ratio; and
Bo is the strength of the magnetic field (in Tesla)
Matching the RF pulse to the Larmor frequency of the radioactive nuclei placed in the magnetic field results in absorption of energy by the radioactive nuclei which causes the nuclei to assume a flip angle, which is defined as the degree to which the nucleus tips toward the X-Y plane and is dependent upon the magnitude and duration of the RF pulse. A flip angle of 90xc2x0 results in revolution of the radioactive nucleus in the X-Y plane.
Upon termination of the RF pulse, T1 spin-lattice relaxation of the radioactive nuclei occurs. The process of T1 spin-lattice relaxation occurs when the nuclei resume their relaxed state along the Z axis (Bo vector). During this relaxation process, the radioactive nuclei undergo coordinated, spontaneous decay and generate energy, which can be in the form of heat electromagnetic radiation and/or radioactive particles, according to the natural decay scheme of the radioactive material, which is a laser as that term is used herein, released along the Z axis or the magnetic field vector. The application of the RF pulse and subsequent energy release in the form of heat, electromagnetic energy and/or particle release through T1 relaxation can be repeated until the radioactive material has undergone complete radioactive decay or decay to a desired level.
In accordance with the invention, a laser beam or emission is also produced by rephasing of the nuclei in the X-Y plane to correct for T2 spin-spin relaxation. Loss of coherence of the nuclei is prevented by applying a 180xc2x0 refocusing RF pulse to the nuclei as in spin-echo MRI imaging where the 180xc2x0 refocusing pulse generates the echo. T2 relaxation may also be corrected by performance of MRI gradient echo technology. Loss of coherence of the nuclei in the X-Y plane is effectively prevented by applying the refocusing pulse very shortly after termination of 90xc2x0 RF pulse, by either spin-echo or gradient echo refocusing technology.
In accordance with another aspect of the invention, laser energy, either in the form of electromagnetic radiation and/or particles, can be released when nuclear materials that are capable of undergoing fission are flipped into the X-Y plane and a 180xc2x0 refocusing pulse or gradient echo pulse is applied thereby causing the radioactive nuclei to reach critical mass in which electromagnetic energy and/or particles are spontaneously released by accelerating and coordinating nuclear fission of these materials.